JP2018176666A - Inkjet recording device, and liquid supply device as well as liquid supply method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording device that can inhibit sedimentation of ink components in a tank, with a simple configuration.SOLUTION: A printer, which forms an image on a roll sheet by supplying ink I stored in a main tank 35 to a recording head 31 through a sub tank 36, comprises: a refilling tube 38 which has an opening/closing valve 40 and suctions ink from a vicinity of a bottom surface 35b in the main tank using a suction pump 39 to refill the ink into the sub tank; and a circulating tube 58 which is branched from the refilling tube, has an opening/closing valve 60 and returns the suctioned ink to the vicinity of liquid level Iu in the tank. A CPU controls the opening/closing valve and the suction pumps before forming the image, so that the ink in the main tank is circulated to make the concentrations of pigment uniform, and then the ink is refilled into the sub tanks and supplied to the recording head.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an ink jet recording apparatus which discharges a liquid such as ink stored in a tank and supplies the liquid to a recording head or the like, a liquid supply apparatus, and a liquid supply method.

  In recent years, a pigment ink used in an inkjet recording apparatus is a solution (liquid) which exists in a particulate form without being dissolved in a solvent. When the pigment ink is stored in the tank and stands by for a long time, the pigment settles in the solvent and a concentration difference occurs in the tank. As described above, when the pigment concentration difference occurs in the ink, the image of each recording medium on which an image is formed varies, and the image quality itself to be formed is also degraded.

  Furthermore, since the pigment ink is sent from the inside of the tank to the recording head through the tube and discharged from the nozzle, the pigment is accumulated and clogged in the tube forming the ink flow path or the nozzle depending on the concentration of the pigment. May occur.

  From this, in addition to the main tank which stores the ink supplied to a recording head, in patent documents 1, the ink jet recording device provided with the sub tank which relays the supply of the ink is indicated. In this inkjet recording apparatus, the tip (open end) of the tube is inserted into the bottom of the main tank and the bottom of the sub tank, and the ink is collected and discharged and circulated, whereby the concentration of the pigment in the ink is made constant. ing. According to this patent document 1, by setting and driving the stirring member in the main tank, the stirring of the ink is promoted in the main tank and it takes too much time to make the concentration of the pigment uniform. There is also disclosed an ink jet recording apparatus provided with a mechanism for avoiding.

2011-121344 gazette

  In the ink jet recording apparatus described in Patent Document 1, the effect of stirring the pigment of the ink in the main tank is expected by returning the ink recovered from the sub tank to the main tank.

  However, in the main tank and the sub tank, only the ink in the vicinity of the respective bottoms is circulated, and it is not possible to expect an efficient stirring effect as a whole. Furthermore, since the circulated ink has a small flow rate per hour and the flow rate can not be increased so much, no stirring effect can be expected. For this reason, in order to make the pigment concentration of the whole ink substantially uniform, it is necessary to perform circulation between the sub tank and the main tank over a considerable time, and it is necessary to carry out the process before the image forming process. There was a problem that it took too much. This problem becomes more pronounced as a main tank capable of storing a large volume of ink, for example, 3 liters of ink, is mounted.

  In addition, since the stirring member is installed for each ink tank to be set, there is a problem that the tank to be replaced as a consumable part becomes expensive.

  An object of the present invention is to provide an ink jet recording apparatus capable of alleviating sedimentation of ink components in a tank with a simple configuration.

  According to an aspect of the invention of an inkjet recording apparatus for solving the above-mentioned problems, there is provided a recording head for recording by discharging ink, and a take-in for taking in the ink from a first area of a tank for storing the ink supplied to the recording head. And an outflow means for causing the ink taken in by the intake means to flow out to the second area on the upper side of the first area of the tank.

  Thus, according to the present invention, the sedimentation of the ink component in the tank can be alleviated.

FIG. 1 is a conceptual schematic diagram for explaining an ink jet recording apparatus according to a first embodiment of the present invention. FIG. 2 is a block diagram for explaining the control system of the system. FIG. 3 is a conceptual structural view for explaining a flow path system for supplying the ink in the main tank. FIG. 4 is a conceptual structural view showing an example in the case where the ink storage amount is different. FIG. 5 is a conceptual schematic diagram for explaining the sedimentation of the pigment according to the passage of time of the ink. FIG. 6 is a flowchart illustrating the ink circulation process. FIG. 7 is a conceptual structural view for explaining an ink jet recording apparatus according to a second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 6 are diagrams for explaining an example of a printer to which an ink jet recording apparatus equipped with a liquid supply apparatus according to a first embodiment of the present invention is applied. FIG. 1 shows an image recording system including the printer. It is a conceptual schematic diagram explaining the whole structure.

  In FIG. 1, a printer 10 is connected to a host apparatus 100 that outputs image data so as to be able to exchange various data, and constitutes an image recording system. The host device 100 is constituted by, for example, a so-called personal computer (PC: Personal Computer), and operates the image recording system by exchanging various data with an external device including the printer 10 . For example, the host device 100 processes the information received from an external device other than the printer 10 by executing software stored in a memory (not shown), and outputs the image data of the processing result generated to the printer 10 . The printer 10 forms an image by recording image data received together with a print command from the host device 100 on a roll paper (recording paper) P of a recording medium passing the image forming area Ar by an inkjet recording method described later. There is.

  Here, in the present embodiment, the case where the printer 10 is connected to the host apparatus 100 as one of the external apparatuses and the image forming system is constructed will be described as an example, but the present invention is not limited to this. For example, only the printer 10 may be connected to the host device 100 to construct an image forming system. Further, the present embodiment may be applied to a case where an image forming system is independently constructed by providing a mechanism for acquiring image data, such as a slot in which the printer 10 sets a memory card. Further, in the present embodiment, a roll paper P of recording paper is described as an example of a recording medium, but the invention is not limited thereto. For example, cut paper which has been cut into a predetermined size may be used. It may be in the form of fanfold paper or the like. Needless to say, the present invention may be applied to a printer that forms an image on a recording medium other than recording paper.

  The printer 10 is configured to include a sheet feeding unit 11, a conveyance unit 12, a recording unit 13, a tank unit 14, and a control unit 15.

  The paper feed unit 11 holds the roll paper P by sandwiching the roll paper P and rotating the paper storage unit 21 in which roll-shaped roll paper P on which an image is formed (hereinafter, simply referred to as printing) is set rotatably. And a paper feed roller pair 22 which is pulled out of the storage unit 21 and fed.

  As a result, in the sheet feeding unit 11, the roll sheet P in the storage unit 21 is nipped by the sheet feeding roller pair 22 and is fed to the conveyance unit 12 from the leading end side. The sheet feeding unit 11 is configured such that a roll motor (not shown) assists the rotation of the roll sheet P in the storage unit 21 and supports sheet feeding and conveyance of the roll sheet P by the sheet feeding roller pair 22. .

  The conveyance unit 12 includes a conveyance belt 25, a conveyance roller pair 26, a carry-out roller pair 27, a conveyance motor 28, and a tension pulley 29. The transport belt 25 is made of an endless belt so as to be capable of cyclic rotation. The pair of transport rollers 26 is disposed on the upstream side (the side of the sheet feeding unit 11) in the transport direction of the image forming area Ar, and is supported in a rotatable manner in a state of sandwiching the transport belt 25. The delivery roller pair 27 is disposed on the downstream side of the image forming area Ar in the transport direction (the opposite side of the sheet feeding unit 11) like the transport roller pair 26 and is freely rotatable in a state of sandwiching the transport belt 25. It is supported by The conveyance motor 28 feeds the conveyance belt 25 wound around the rotation shaft 28 a together with the conveyance roller pair 26 and the discharge roller pair 27 in the rotational direction by rotational power. The tension pulley 29 applies a constant tension to the transport belt 25 in a wound state.

  Thereby, in the conveyance unit 12, the image forming area Ar is positioned on the upper surface of the conveyance belt 25 stretched between the conveyance roller pair 26 and the discharge roller pair 27, and the conveyance belt 25 is It is cyclically rotated repeatedly by the rotation of the rotation shaft 28a. Therefore, in the transport unit 12, the roll paper P fed from the paper feed unit 11 is nipped between the transport roller pair 26 and fed together with the transport belt 25 so as to pass through the image forming area Ar and transport direction It is transported to A. Thereafter, in the transport unit 12, the roll paper P passing through the image forming area Ar is delivered to the delivery roller pair 27 and delivered from the transport belt 25 onto the delivery unit 30. Although the paper discharge unit 30 omits the detailed description of the structure, for example, the paper discharge unit 30 may be structured to roll up and store the image-formed roll paper P, or a table to be cut into a predetermined size and stacked. May be provided.

  The recording unit 13 is constructed by a plurality of recording heads 31 which eject ink, and recording heads 31 K and 31 C for each color ink of black (K), cyan (C), magenta (M) and yellow (Y). , 31M, 31Y. The recording units 13 are arranged in parallel such that the recording heads 31 K, 31 C, 31 M, and 31 Y are sequentially arranged in the conveyance direction A of the conveyance belt 25 of the conveyance unit 12. The recording unit 13 forms a full color image on one side of the roll paper P by sequentially ejecting the ink of each color toward the image forming area Ar on each of the recording heads 31. Needless to say, the number of recording heads 31 and the color tone described in the present embodiment are merely examples, and the present invention is not limited to this.

  The recording head 31 of the recording unit 13 extends in the width direction of the conveyance belt 25 (direction orthogonal to the conveyance direction A), and is a so-called full line in which nozzles (not shown) for discharging (jetting) ink are arranged. It is made in the form of a head. The recording head 31 is manufactured such that the discharge range of the ink is longer than the width of the roll paper P. The recording head 31 is not limited to the form of a line head. For example, a so-called carriage type may be adopted, which is compact and discharges ink in the width direction of the roll paper P while reciprocating. Further, it goes without saying that the recording head 31 may be of a type using either a heating element or a piezoelectric element as a method of discharging the ink I.

  Here, the recording head 31 of the recording unit 13 of the present embodiment is held by a mechanism (not shown) movable in the conveyance direction A and the vertical direction B, and utilizes the driving force of the motors 33 and 34 shown in FIG. Is movably supported. As a result, the recording head 31 can slide and reciprocate in the transport direction A of the roll paper P, and can move up and down in the vertical direction B with respect to the roll paper P.

  Further, the removable cap 32 is disposed adjacent to each other in the transport direction A on the side of the formation surface 31 a of the nozzle that ejects the ink. The recording head 31 is slid in the horizontal direction to advance in the transport direction A and then lowered in the vertical direction B while avoiding a collision with the cap 32 by raising it in the vertical direction B, so that the cap 32 It is attached to the nozzle formation surface 31a. For example, when the nozzle forming surface 31a is exposed to the atmosphere during storage of the printer 10 or printing standby, for example, the solvent of the ink in the vicinity of the outlet of the nozzle is volatilized to increase the viscosity. Solidification occurs. Further, in the recording head 31, dust adheres to the ink, and the discharge quality of the ink is lowered, and the image quality is deteriorated. By attaching the cap 32 to the recording head 31, the occurrence of these inconveniences can be prevented in advance. The recording head 31 may be restored to the operable state by the reverse procedure. That is, the recording head 31 discharges the ink onto the roll paper P by raising the recording head 31 in a direction away from the cap 32 and slidingly moving it in the reverse horizontal direction and then lowering it and fitting it into a positioning opening (not shown). Positioning is fixed at the image forming position.

  Further, as described above, the recording head 31 of the present embodiment has a function of recovering the quality of the discharged ink, in addition to the attachment and detachment of the cap 32 in order to avoid the inconvenience due to the exposure of the nozzle forming surface 31a. It is done. The recording unit 13 is, for example, ink in the vicinity of the discharge port of the nozzle by applying a negative pressure by a pump (not shown) to a space formed between the recording head 31 and the cap forming surface 31a. Is equipped with a recovery mechanism (not shown) to recover the quality by The recovery mechanism is not limited to this, and for example, the quality of the ink at the time of operation may be recovered by causing the recording head 31 to perform the preliminary ink discharge operation before the operation. Further, in addition to the cap 32, a wiper blade made of rubber or the like for wiping the nozzle formation surface 31a of the recording head 31 may be attached to execute the cleaning operation before the operation. The sub tank 36 is installed at a height at which a predetermined negative pressure can be applied to the nozzle formation surface 31 a of the recording head 31.

  The tank unit 14 is provided with a plurality of main tanks 35 for storing the ink which the recording head 31 of the recording unit 13 discharges onto the roll paper P. The tank unit 14 has main tanks 35K, 35C, 35M and 35Y for each color of black (K), cyan (C), magenta (M) and yellow (Y), and recording heads 31K, 31C, 31M, Each color ink is supplied to 31Y.

  As shown in FIG. 2, the control unit 15 is connected to the CPU 41 so that the program ROM 42, the image memory 43, the work RAM 44 and the operation panel 45 can exchange various information. The CPU 41 executes the control program stored in the program ROM 42, and based on various sensor information temporarily stored in the work area of the work RAM 44, various setting instruction information input from the operation panel 45, etc. Control overall. Thus, the CPU 41 carries out an image forming process for recording the image data received from the host device 100 on the roll paper P by the inkjet recording method. The program ROM 42 stores a processing program for executing an ink replenishment procedure, which will be described later, and the like, and various tables for storing necessary fixed data.

  The control unit 15 is connected to the CPU 41 so that the host apparatus 100 can exchange various information via the interface controller 46. In addition, a sensor group 50 installed in each of the paper feed unit 11, the conveyance unit 12, the recording unit 13, and the tank unit 14 constituting the printer 10 is connected to the CPU 41 so that various information can be acquired via the input port 47. ing. The sensor group 50 detects and acquires various information in order to perform a required operation. For example, a paper leading edge sensor 50p that detects the leading edge of the roll paper P, and an ink remaining amount sensor that detects the remaining amount of ink 50i etc. are installed appropriately.

  The control unit 15 is connected to the CPU 41 so that the recording unit 13 can exchange various information via the recording head control circuit 48. The print head control circuit 48 generates drive signals for each color ink based on image data sent from the CPU 41 and controls the print heads 31 K, 31 C, 31 M, and 31 Y to appropriately eject each color ink. . The CPU 41 receives various information on the recording head 31 side via the recording head control circuit 48, for example, sensor information for detecting the movement of the recording head 31, the attachment of the cap 32, etc., and drives the motor group described later. It is supposed to control.

  The CPU 41 of the control unit 15 relays each color image data to be processed by the recording head 31 by performing bit map development and raster division while temporarily storing image data received together with a print command from the host device 100 in the image memory 43. Do. The CPU 41 controls the recording head control circuit 48 to drive the respective color recording heads 31 K, 31 C, 31 M, and 31 Y to which the respective color image data is allocated, thereby discharging the respective color inks toward the roll paper P to form an image.

  At this time, the CPU 41 controls the discharge timing of each color ink of the recording head 31 based on the detection information of the paper leading edge sensor 50p of the sensor group 50 that detects the leading edge of the roll paper P carried into the image forming area Ar. The CPU 41 sequentially relays the image data developed in the image memory 43 and discharges the ink of each color of the recording head 31 so as to synchronize with the roll paper P carried into the image forming area Ar. Image formation on paper P. Note that on the roll paper P, each color ink of black (K), cyan (C), magenta (M) and yellow (Y) is selectively selected sequentially from the recording head 31K to the recording heads 31C, 31M, and 31Y. The full-color image is formed by being ejected and superimposed.

  The CPU 41 is connected to the motor drive unit 51 via the output port 49 so as to be able to output various types of information. To the motor drive unit 51, various motors such as the above-described transport motor 28 and a suction pump 39 described later are connected so as to be able to receive drive signals. The motor drive unit 51 drives the elevation motor 33 to move the recording head 31 of the recording unit 13 in the vertical direction B, and the slide motor 34 to slide the recording head 31 in the conveyance direction A based on various instructions from the CPU 41 It is connected to be able to receive a signal. Thereby, the motor drive unit 51 generates a drive signal based on, for example, the conveyance instruction of the roll paper P from the CPU 41, and drives the conveyance motor 28 of the conveyance unit 12 to make the roll paper P in the image forming area Ar. Transport to pass through. The motor drive unit 51 generates an elevation signal and a slide signal of the recording head 31 based on the attachment / detachment instruction of the cap 32 from the CPU 41, and drives the elevation motor 33 and the slide motor 34 to form the nozzles of the recording head 31. The cap 32 is attached to and detached from the surface 31a.

  Incidentally, in the tank unit 14, as shown in FIG. 3, the sub tank 36 is disposed between the recording head 31 and the main tank 35. The sub tank 36 is connected to the recording head 31 so as to be able to flow the ink I by one supply tube 37, and is connected to the main tank 35 so as to be able to flow the ink I by the replenishment tube 38. That is, the tank unit 14 is constructed to receive the ink I replenished from the main tank 35 via the replenishment tube 38 by the sub tank 36 and supply it to the recording head 31 while temporarily storing it. In short, the ink I in the main tank 35 is relayed to the sub tank 36 and supplied to the recording head 31. That is, the ink I in the main tank 35 is supplied through the refilling tube 38 to the sub tank 36 and the recording head 31 as a supply destination.

  The sub tank 36 is manufactured in a volume capable of storing a small volume of ink I, since the ink I replenished via the replenishment tube 38 is supplied to the recording head 31 at any time via the supply tube 37. The main tank 35 is manufactured in a volume capable of storing a large volume of ink I.

  In the sub tank 36, the suction port 37i at the opposite end of the supply tube 37 connected to the recording head 31 is inserted to the vicinity of the bottom surface 36b so as to be able to suction the ink I. Further, the sub tank 36 is positioned and fixed so that the discharge port 38 o at one end side of the refilling tube 38 is positioned in the vicinity of the liquid level iu of the ink I of a fixed amount. As a result, in the sub tank 36, the ink I discharged from the discharge port 38o of the refilling tube 38 is replenished (supplied) from the liquid surface iu side and sucked from the suction port 37i of the supply tube 37 on the bottom surface 36b. Therefore, the sub tank 36 can supply the recording head 31 with stirring (mixing) a small amount of stored ink I.

  The refilling tube 38 has the discharge port 38o at one end located near the liquid surface iu of the sub tank 36, while the suction port 38i at the other end works near the bottom 35b of the main tank 35 with the ink I. It is plugged in for retrieval. In the refilling tube 38, a suction pump 39 and an open / close valve 40 are provided between the discharge port 38o and the suction port 38i. The refilling tube 38 is taken in by sucking the ink I near the bottom (the first region) of the main tank 35 from the suction port 38i by opening the on-off valve 40 and driving the suction pump 39, and the sub-tank 36 is It is installed to supply (replenish) from the discharge port 38o. The term “near the bottom surface 35 b of the main tank 35” is also referred to simply as “bottom surface vicinity (near the bottom surface 35 b)” below.

  Between the suction pump 39 and the on-off valve 40, the replenishment tube 38 has a flow path formed by connecting one end side of the circulation tube 58 to bifurcate the ink I.

  The circulation tube 58 has a branch port 58s at one end connected to the refilling tube 38 and a discharge port 58o at the other end, which is located near the liquid level Iu above the bottom surface 35b of the main tank 35 (second region) Ink I can be discharged. Thus, the circulation tube 58 takes in the ink I flowing in the refill tube 38 from the branch port 58s and discharges the ink I from the discharge port 58o, thereby returning the ink I into the main tank 35.

  The circulation tube 58 is provided with an open / close valve 60 between a branch port 58s of the refill tube 38 and an outlet port 58o. The circulation tube 58 is driven by the suction pump 39, and the ink I in the vicinity of the bottom surface 35b of the main tank 35 sucked and taken in from the suction port 38i of the refilling tube 38 is introduced from the branch port 58s and is again mained from the discharge port 38o. Discharge to the vicinity of the liquid level Iu of the tank 35. That is, with the tank unit 14 with the open / close valve 60 opened and the open / close valve 40 closed, the suction pump 39 is driven to supply the ink I in the main tank 35 with the replenishment tube 38 and the circulation tube 58. It is installed to circulate through. The term “near the vicinity of the liquid level Iu of the ink I” is also referred to simply as “liquid level vicinity (near the liquid level Iu)” below.

  That is, the suction port 38i of the refilling tube 38 constitutes a bottom portion intake port (intake means), and the discharge port 58o of the circulation tube 58 constitutes a liquid surface return port (outflow means). The refilling tube 38 and the circulation tube 58 are in fluid communication with the ink I outside the main tank 35 between the suction port 38i and the discharge port 58o. In short, the replenishment tube 38 and the circulation tube 58 constitute an ink flow path and a liquid flow path which are circulated without being confused with the ink I in the main tank 35, and the ink passing through the ink flow path and the inside of the main tank 35 It constitutes a circulation route. The refilling tube 38, the suction pump 39 and the open / close valve 40 constitute a supply means for supplying the ink I in the main tank 35 to the recording head 31 via the sub tank 36. The circulation tube 58 and the on-off valve 60 are added to the refilling tube 38, the suction pump 39, and the on-off valve 40, and an ink flow mechanism that causes the ink I in the main tank 35 to flow in the circulation path via the ink flow path. And the liquid flow mechanism is configured.

  The circulation tube 58 includes a tube body 58 b, a bellows tube 64, and a float 65. The tube body 58 b is connected to the upper surface 35 u of the main tank 35. The bellows-like tube 64 is formed to be stretchable, and is suspended from the upper surface 35 u of the main tank 35 in communication with the tube main body 58 b. The float 65 has a through hole 65 h communicating with the bellows tube 64 and floats on the liquid level Iu (above the liquid level) of the ink I in the main tank 35.

  With this structure, the circulation tube 58 discharges the ink I sucked from the vicinity of the bottom surface 35b of the main tank 35 via the replenishment tube 38 to the vicinity of the liquid level Iu via the bellows tube 64 and the through hole 65h of the float 65. It is built to be. In the through hole 65h of the float 65, an inlet 65hi communicating with the bellows tube 64 is opened on the upper surface side. Further, the through hole 65h of the float 65 is formed in a shape bent downward toward the liquid surface Iu of the ink I from the inlet 65hi and then bent in the horizontal direction, and the outlet 65ho is opened on the side surface to discharge the outlet It is supposed to function as 58o.

  Here, the bellows-like tube 64 is interlocked with the float 65 located at the lower end moving up and down (following and moving) on the liquid surface according to the height of the liquid level Iu of the ink I in the main tank 35. Stretch. Thereby, even if the liquid level Iu of the ink I of the main tank 35 falls from the state shown in FIG. 4A to the state shown in FIG. And allow the float 65 to descend. Therefore, the circulation tube 58 can smoothly return the circulating ink I to the vicinity of the liquid level Iu of the ink I in the main tank 35. Further, the float 65 is movably held in the vertical direction by a rod-like slider 69 extended in the vertical direction at a position close to the one side wall 35s of the main tank 35.

  In addition, in the main tank 35, a communication pipe 70 which connects the inside and the outside to the upper surface 35u is installed. Thus, when the ink I stored in the main tank 35 is sucked through the refilling tube 38, the outside air is allowed to flow into the inside through the communication pipe 70, and the negative pressure is avoided. , The suction of the ink I is not prevented.

  In addition, the float 65 is attached on the liquid level Iu of the main tank 35 so that a boat 66 floating in a state of being extended so as to spread in one direction away from the slider 69 is integrated with the bottom surface 65b. The boat 66 is made of a material having a specific gravity which floats alone on the liquid level Iu of the ink I, even if it is not formed into a boat-like shape, which will be described later, like the float 65.

  The boat 66 is formed in, for example, a frame-shaped hull shape including a frame plate 66 f surrounding the periphery of the bottom plate 66 b extended to the vicinity of the side wall 35 s of the main tank 35. The boat 66 is floated on the liquid level Iu of the ink I in the main tank 35 together with the float 65, and an inner space S of the main tank 35 is surrounded by the bottom plate 66b and the frame plate 66f. And the lower space Sd below. In the boat 66, outlets 66d open at a plurality of locations in the plane of the bottom plate 66b that divides the floating space (upper space) Su from the upper part of the lower space Sd of the internal space S storing the ink I in the main tank 35 It is done. The outlet 66 d of the boat 66 opens at a plurality of spaced apart intervals so as to expand in the area direction of the bottom plate 66 b of the boundary surface that divides the internal space S of the main tank 35 into the lower space Sd and the floating space Su. Is formed.

  As a result, the boat 66 of the float 65 takes in the ink I taken in from the refill tube 38 into the circulation tube 58 and discharged from the discharge port 58o at the end of the through hole 65h and floats up space Su within the bottom plate 66b and the frame plate 66f. Accept to be stored inside. In other words, the boat 66 restricts the flow of the ink I in the downward direction without resistance. The boat 66 is separated from the slider 69 and spreads in a direction parallel to the liquid surface of the ink I while temporarily storing the ink I from the outlets 66 d at a plurality of locations from the lower space Sd of the main tank 35. It can be made to flow down and settle so as to spread inside. That is, the boat 66 functions as a flow resistance member that blocks the flow operation of discharging from the discharge port 58 o of the float 65 of the circulation tube 58 and mixing in the ink I of the main tank 35. The boat 66 spreads from the outlets 66 d in the vicinity of the liquid level Iu of the main tank 35 the ink I to be sucked from the suction port 38 i of the refilling tube 38 near the bottom surface 35 b of the main tank 35 and circulated by the circulation tube 58. It is allowed to settle (mix) as it is. Although the bottom plate 66b of the boat 66 is formed to extend to a position approaching the side wall 35s of the main tank 35 by way of example, it is not limited thereto. For example, sufficient effects can be obtained even in the state where the bottom surface of the boat is spread over the liquid level Iu of the ink I with a certain area.

  By the way, since the supply of the ink I is also stopped when the image forming operation is stopped, the tank unit 14 is in a state where the ink I is filled in the sub tank 36, the replenishment tube 38, the circulation tube 58, etc. It is supposed to wait and then wait.

  At this time, as shown in FIG. 5, the ink I stored in the main tank 35 or the sub tank 36 is a solution (liquid) in which the particulate pigment c is dispersed in the solvent s. In the ink I, the pigment c is dispersed in the solvent s, and the colors of black (K), cyan (C), magenta (M) and yellow (Y) are developed. In the ink I, the pigment c tends to descend, that is, settle, in the solvent s with the passage of time in the resting state. For this reason, in the ink I, the pigment c gradually precipitates with the passage of time in a resting state of approximately monthly units, and the pigment c precipitates near the bottom surface 35b and the concentration αb becomes thick, while the pigment c near the liquid surface Iu Concentration α u becomes thinner. For example, when the main tank 35 is shaken and set in the tank unit 14 of the printer 10, as shown in FIG. 5A, the pigment c is in a state of concentration α0 where the pigment c is dispersed substantially uniformly. After that, as shown in FIG. 5 (b) to FIG. 5 (c), the pigment c precipitates and precipitates gradually with the passage of time in the resting state, as shown in FIG. 5 (c). There is a difference between the concentration αu of the second region and the concentration αb near the bottom surface 35b, and a concentration distribution spreading in the vertical direction is generated. The dispersion state of the pigment c shown in FIG. 5 of the ink I is merely an example, and generally differs depending on the viscosity of the solvent s and the particle size and shape of the pigment c.

  Specifically, the concentration α of the pigment c of the ink I in the main tank 35 gradually settles in accordance with the elapsed time (retention time described later) T from the concentration α 0 at which the pigment c disperses uniformly in the resting state It changes with the extent to which it precipitates. For this reason, the concentration α u (t) of the pigment c near the liquid level I u changes in the direction of becoming thinner according to the elapsed time T, and is stabilized and stabilized. In addition, the concentration αb (t) of the pigment c near the bottom surface 35b changes in the direction of becoming thicker according to the elapsed time T, and becomes stable and in an equilibrium state. The concentration α of the pigment c of the ink I follows the dispersion characteristics of the pigment c in the solvent s.

  Therefore, the CPU 41 of the control unit 15 opens the on-off valve 40 of the refill tube 38 to drive the suction pump 39 with the on-off valve 60 of the circulation tube 58 closed. Thereby, the CPU 41 sucks the ink I of the concentration αb near the bottom surface 35 b of the main tank 35 from the suction port 38 i of the refilling tube 38, discharges it from the discharge port 38 o and refills the inside of the sub tank 36.

  At this time, the CPU 41 closes the on-off valve 40 of the refill tube 38, opens the on-off valve 60 of the circulation tube 58, and sets the suction pump 39 in the program ROM 42 in advance. It drives only for the drive time t which is being done. Thus, the ink I of concentration αb near the bottom surface 35b of the main tank 35 sucked from the suction port 38i of the refilling tube 38 is discharged from the discharge port 58o of the circulation tube 58 into the boat 66 of the float 65 and on the bottom plate 66b. Flow in the direction of separation. The ink I having a concentration αb flowing in the boat 66 is circulated so as to be returned to the ink I having a concentration αu in the main tank 35 by flowing down from the outlet 66d opened at a plurality of locations on the bottom plate 66b. Be done. In short, the CPU 41 controls the drive of the suction pump 39 and the on-off valves 40 and 60 to mix the ink I in the vicinity of the bottom surface 35b of the main tank 35 with the ink I in the vicinity of the liquid level Iu, to obtain approximately uniform density α0. It is supposed to be adjusted.

  Here, the drive time t set in the program ROM 42 may be set to execute the above circulation operation as the optimum time according to the density change of the pigment c of the ink I. The pigment c in the ink I is in the vicinity of the liquid level Iu according to the residence time T which settles after being set in the printer 10 of the main tank 35 shaken or from the uniform dispersion state after the above circulation operation. The concentration αu is thin, and the concentration αb near the bottom surface 35b changes in the direction of becoming denser. From this, the driving time t to be set is to make the whole of the ink I in the main tank 35 have the concentration α0 at which the pigment c is uniformly dispersed by the above circulation operation according to the residence time T in which the pigment c settles. The necessary circulation time may be obtained in advance by a test or the like. For example, a map or the like for determining the driving time t in accordance with the residence time T may be prepared and set in the program ROM 42 or the like, and the circulating operation may be performed in the optimum driving time t. In the ink I in the main tank 35, the concentration αu of the pigment c in the vicinity of the liquid level Iu is reduced, and the concentration αb of the pigment c in the vicinity of the bottom surface 35b is increased to be in equilibrium. For this reason, when in the equilibrium state, the circulation time necessary to make the entire ink I in the main tank 35 have the concentration α0 for uniformly dispersing the pigment c by the above circulation operation is obtained in advance by a test or the like. The above circulation operation may be performed uniformly as the driving time t.

  The CPU 41 has a timer function for measuring the current time, and stores the set time of the main tank 35 and the end time of the previous circulation operation in the work RAM 44, whereby the residence time for the pigment c in the ink I to settle Calculate (acquire) T from the current time. The CPU 41 refers to the map in the program ROM 42 using the residence time T, determines the drive time t for executing the above-mentioned circulation operation, and drives the suction pump 39 together with the on-off valves 40 and 60. Here, although the case where the CPU 41 determines the driving time t according to the residence time T as the circulation process of the ink I will be described as an example in the present embodiment, the present invention is not limited thereto. For example, the CPU 41 may adjust the suction intensity of the suction pump 39 to execute the above circulation operation with the same flow rate of the ink I.

  Specifically, the CPU 41 starts the liquid supply process shown in the flowchart of FIG. 6 prior to the image forming process of recording the image data received from the host apparatus 100 on the roll paper P by the inkjet recording method. The CPU 41 circulates the ink I in the main tank 35 from the vicinity of the bottom surface 35b to the vicinity of the liquid level Iu according to the control program in the program ROM 42 and returns the ink I to the subtank 36. Perform liquid supply processing to replenish. That is, the CPU 41 refills the sub-tank 36 with the ink I after the circulation control processing for uniformly mixing the concentration α of the pigment c of the ink I in the main tank 35 before the image forming processing. Execute the liquid supply control process (liquid supply method) shown.

  First, as shown in FIG. 6, the CPU 41 acquires the remaining amount of each color ink I in the sub tank 36 from the sensor information of the ink remaining amount sensor 50i of the sensor group 50 (step S11). Next, the CPU 41 repeatedly checks whether the remaining amount of the ink I in the sub tank 36 falls below a preset threshold and is consumed to such a degree that replenishment is necessary (step S12).

  In step S12, the CPU 41 confirms the ink I which needs to be replenished to the sub tank 36 from the work RAM 44 from the setting time of the main tank 35 of the ink I of the corresponding color or the latest time of the circulation operation end time. Read out (step S13). Next, the CPU 41 calculates the retention time T of the ink I in the main tank 35 of the corresponding color from the latest time and the current time (step S14).

  Next, the CPU 41 refers to the map in the program ROM 42 based on the residence time T to determine the driving time t for executing the above-mentioned circulation operation (step S15). After this, the CPU 41 executes processing for continuing the circulation operation for driving the suction pump 39 for the driving time t after closing the open / close valve 40 and opening the open / close valve 60 (step S16).

  Thereby, the ink I in the main tank 35 is returned to the vicinity of the liquid level Iu from the vicinity of the bottom surface 35b via the circulation tube 58 etc. and mixed, so that the concentration c uniformly disperses the pigment c as a whole. Mixed early.

  Next, the CPU 41 opens the on-off valve 40 and closes the on-off valve 60, and then drives the suction pump 39 to execute the process of replenishing the ink I of the replenishment amount set in advance from the main tank 35 to the sub tank 36. (Step S17), this process ends.

  Here, in the liquid supply control process, the ink I in the vicinity of the bottom surface 35b of the main tank 35 is sucked and taken in from the suction port 38i of the refilling tube 38 and discharged from the discharge port 58o of the circulation tube 58. A liquid surface returning process is performed to return the ink I to the vicinity of the liquid surface Iu. At this time, a circulating flow process of flowing through a circulation path passing through the inside of the main tank 35 after passing through the circulation tube 58 etc. so that the ink I to be circulated is not mixed with the ink I in the main tank 35 Is done. Thereafter, the on / off valves 40 and 60 are switched to supply the ink I adjusted to the uniform concentration α0 of the pigment c by discharging it from the discharge port 38o of the refilling tube 38 into the supply destination sub tank 36 and supplying it. A process is also performed.

  As a result, the sub tank 36 is mixed from the vicinity of the bottom surface 35 b to the vicinity of the liquid level Iu for a drive time t corresponding to the residence time T of the ink I in the main tank 35, whereby the uniform concentration α0 of pigment c is obtained. The adjusted ink I is replenished.

  As described above, in the printer 10 of the present embodiment, the ink I in the main tank 35 can be supplied so as to be replenished to the sub tank 36 after being adjusted to the concentration α0 at which the pigment c is uniformly dispersed. Therefore, the ink I having the uniform concentration c of the pigment c is stably replenished to the sub tank 36 and supplied to the recording head 31.

  Therefore, the printer 10 can stably supply the ink I of the pigment c of uniform density α 0 to the recording head 31 without installing the stirring function of the ink I in the main tank 35. For this reason, even in the case of the ink I in which the pigment c which is likely to generate a density difference is dispersed in the solvent s, it is possible to form a high quality image without variation.

  Therefore, an inexpensive printer 10 capable of forming high-quality images on roll paper P with ink I having a uniform density α 0 and stable pigment c without making the main tank 35 expensive with the stirring member of ink I Can be provided.

The distance from the liquid level Iu to the outlet 66 d is preferably equal to or less than the distance from the bottom surface 35 b of the tank 35 to the suction port 38 i of the refilling tube 38.
Since the settling speed of the pigment c is constant, the degree of decrease of the pigment concentration in a portion separated by a predetermined distance from the ink surface is almost equal to the degree of increase of the pigment concentration in a portion separated by the same distance from the tank bottom. Therefore, with the above configuration, when mixing the ink at the bottom with the increased density and the ink near the liquid surface with the decreased density, the ink concentration can be easily made uniform.

  Next, FIG. 7 is a view for explaining an example of a printer to which an ink jet recording apparatus equipped with a liquid supply apparatus according to a second embodiment of the present invention is applied, and FIG. It is a conceptual block diagram. In addition, since the present embodiment is configured substantially the same as the above-described embodiment, the same reference numerals are given to the same configurations, and the characteristic portions will be described.

  In FIG. 7, in the tank unit 14 of the printer 10, the main tank 35 and the sub tank 36 are connected so as to allow the ink I to flow by the replenishment tube 38 and the circulation tube 78 without interposing the on-off valves 40 and 60.

  The circulation tube 78 has a suction port 78i at one end thereof inserted in the vicinity of the liquid surface iu in the sub tank 36 so as to be able to suction the ink I in the opposite direction to the refill tube 38. At the other end of the circulation tube 78, the circulation tube 58 of the above embodiment is replaced by the bellows-like tube 64, whereby the ink I from the discharge port 58o of the float 65 floating on the liquid level Iu of the main tank 35 is obtained. It is built to be drainable.

  The tank unit 14 has one suction pump 79 installed in the circulation tube 78 as well as the refill tube 38. The tank unit 14 of the present embodiment drives the suction pumps 39, 79 without requiring the opening and closing operation of the opening and closing valves 40, 60.

  Thus, the ink I in the main tank 35 is sucked from the suction port 38i of the refill tube 38 and refilled into the sub tank 36 from the discharge port 38o. At the same time, the ink I in the sub tank 36 is sucked from the suction port 78i of the circulation tube 78 and returned to the main tank 35 from the discharge port 58o. For this reason, the tank unit 14 of this embodiment is configured to be able to execute a circulation operation of returning the ink I sucked from near the bottom surface 35b of the main tank 35 to near the liquid level Iu by driving the suction pumps 39 and 79. ing.

  That is, as in the above-described embodiment, the suction port 38i of the refilling tube 38 constitutes a bottom inlet port (taking-in means), and the outlet port 58o of the float 65 of the circulation tube 78 constitutes a liquid level inlet port. Then, a sub-tank 36 is added to the refilling tube 38 and the circulating tube 78 to form a circulating flow path, and suction pumps 39 and 79 are added to these to constitute a supply means.

  Therefore, the CPU 41 of the control unit 15 is configured to execute a circulation operation for simultaneously driving the suction pumps 39 and 79 without requiring the opening and closing operation of the opening and closing valves 40 and 60 of the above-described embodiment. That is, the CPU 41 executes circulation control processing for simultaneously driving the suction pumps 39 and 79 when executing the above-described circulation operation, as in the above-described embodiment. Thereafter, in the liquid supply control process (liquid supply method), the CPU 41 drives only the suction pump 39 to replenish the ink I from the main tank 35 to the sub tank 36.

  Accordingly, even in the main tank 35 of the present embodiment, the ink I is adjusted to have the pigment c of uniform density α0 by passing the ink I through the circulation tube passing through the circulation tube 78 from the replenishment tube 38 through the sub tank 36. The I can be replenished to the sub tank 36.

  As described above, in the printer 10 of the present embodiment, in addition to the functions and effects of the above-described embodiment, the installation and the drive control of the on-off valves 40 and 60 are omitted. The image can be formed by supplying the ink I of uniform density.

  Here, in the above-mentioned embodiment, although a case where bottom 35b of main tank 35 is formed in a level plane is explained as an example, it does not restrict to this. For example, although not shown in the drawings, the bottom surface 35b of the main tank 35 may be formed into an inclined surface shape which inclines so that the vicinity of the suction port 38i of the refilling tube 38 is the bottom and has the deepest portion . In this case, the tank unit 14 can collect the pigment c precipitated in the ink I at the deepest portion of the bottom surface 35b of the inclined surface to ensure a stable density change, and is formed by the ink I ejected from the recording head 31. Images can be made more stable and high quality.

  Further, “recording” and “image formation” used in the description of the above-described embodiment is not limited to the case of revealing significant information such as characters and figures, and may or may not be significant. In addition, “recording” and “image formation” mean to widely form an image, a pattern, a pattern, etc. on a recording medium, regardless of whether it is manifested so as to be perceived visually. Do. The recording may include processing of the medium.

  The recording medium is not limited to sheet-like paper used in office equipment and the like, and can widely be formed by the ink I, including cloth, plastic film, metal plate, glass, ceramics, wood, leather, etc. What if it is

  In the embodiment described above, the ink I used in the inkjet recording method is described as an example, but the present invention is not limited to this. For example, as in the above-mentioned "recording", the ink is applied onto the recording medium to form an image, a pattern, a pattern, etc. or process the recording medium, or coagulate or insolubilize a coloring agent in the ink. The present embodiment may be applied, including a solution such as a liquid to be subjected to a treatment such as

  Furthermore, in the above-mentioned embodiment, although the case where the remaining amount of the ink I in the sub tank 36 is detected by the sensor is described as an example, the present invention is not limited to this. For example, the discharge amount of the ink I of the recording head 31 may be integrated and detected by subtracting the volume from the sub tank 36.

  Here, the present invention can be widely applied to liquid supply devices that supply various liquids, and liquid discharge devices that can discharge various liquids. For example, the present invention is not limited to the ink in which a pigment is dispersed in a solution, and can be suitably applied to a device that discharges a liquid in which precipitated particulate material is dispersed in a solvent. Further, the present invention is directed to an apparatus that performs various processing (recording, processing, coating, irradiation, reading, inspection, etc.) on various media such as sheets using a liquid discharge head capable of discharging liquid. Is also applicable. The medium (including the recording medium) includes various media to which the liquid including the ink is applied, regardless of the material, such as paper, plastic, film, fabric, metal, flexible substrate, and the like.

  While embodiments of the present invention have been disclosed, it will be apparent to one skilled in the art that modifications can be made without departing from the scope of the present invention. All such modifications and equivalents are intended to be included in the following claims.

10 Printer (inkjet recording device)
31 Recording head (supply destination)
35 Main tank 35 b Bottom surface 36 Sub tank (supply destination)
37 Supply tube 38 Refilling tube (supply means)
38i Suction port (bottom intake port, intake means)
38o outlet 39, 79 suction pump (supply means)
40, 60 on-off valve (supply means)
41 CPU (control unit)
58, 78 Circulation tube 58o Exhaust port (liquid level return port, outflow means)
65 float 65 b bottom surface 64 bellows tube 100 host device c pigment I ink (solution, liquid)
Iu Liquid level P Roll paper (recording medium)
s Solvent

Claims (9)

A recording head that performs recording by discharging ink;
A take-in means for taking in ink from a first area of a tank for storing the ink to be supplied to the recording head;
Effluent means for causing the ink taken in by the take-in means to flow out to the second area on the upper side of the first area of the tank;
An inkjet recording apparatus comprising:   The ink jet recording apparatus according to claim 1, wherein the outflow means is disposed near the liquid surface of the ink. It has a float that moves following the level of the ink,
The ink jet recording apparatus according to claim 2, wherein the outflow means moves in conjunction with the float.   The said outflow means has a flow resistance member which accelerates | stimulates flowing so that the flowed-out ink spreads in a direction parallel to the liquid level of the said ink. The inkjet recording device as described.   5. The ink jet recording apparatus according to claim 4, wherein the outflow means has an ink outlet port in the flow resistance member.   2. The apparatus according to claim 1, wherein the distance from the outlet through which the outflow means discharges the ink to the liquid surface of the ink is equal to or less than the distance from the intake through which the intake means takes the ink to the bottom of the ink. An ink jet recording apparatus according to any one of claims 5 to 10.   The ink jet recording apparatus according to any one of claims 1 to 6, wherein the take-in means and the outflow means are provided in the tank for storing the ink supplied to the recording head. A tank for storing liquid,
Means for taking in liquid in the first region of the tank;
A sub-tank for storing the liquid taken in by the taking-in means;
Effluent means for allowing liquid in the sub tank to flow out to a second area above the first area of the tank;
Supply means for supplying the liquid of the sub tank to a predetermined supply destination;
The liquid supply device characterized by having. A taking-in process for taking up the liquid in a first region of the tank for storing the liquid;
An outflow step of causing the liquid taken in in the intake step to flow out to a second region on the upper side of the first region of the tank;
A liquid supply method characterized in that the liquid in the tank is supplied to a predetermined supply destination.

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